Pre-heater for an electrostatographic reproduction apparatus fusing assembly

Abstract

A pre-heater for a fusing assembly for an electrostatographic reproduction apparatus, in which an image-wise pattern of pigmented marking particles is fixed to a receiver member transported along a travel path in operative relation with said fusing assembly. The pre-heater as described includes a housing defining an internal chamber. The housing internal chamber defines an opening adjacent to the receiver member travel path. A heating element is located within the housing internal chamber. An airflow system is provided including a blower, and a distribution plenum in flow communication between the blower and the heating element. An impingement member is positioned in the chamber opening adjacent to said travel path. An impingement plenum is in flow communication between the heating element and the impingement member, and a return conduit is in flow communication between the opening and the blower. Accordingly, air from the blower is delivered through and heated by the heating element, impinges upon a receiver member bearing a marking particle image in the opening, and is returned to the blower while being substantially prevented from escaping from the chamber.

What is claimed is:  
     
       1. In a fusing assembly for an electrostatographic reproduction apparatus, in which an image-wise pattern of pigmented marking particles is fixed to a receiver member transported along a travel path in operative relation with said fusing assembly, said fusing assembly including a pre-heater for facilitating efficient fusing assembly operation and gloss control, said pre-heater comprising: 
       a housing defining an internal chamber open adjacent to said receiver member travel path;  
       a heating element within said housing internal chamber;  
       an airflow system including a blower, a distribution plenum in flow communication between said blower and said heating element, an impingement member in said chamber opening adjacent to said travel path, an impingement plenum in flow communication between said heating element and said impingement member, and a return conduit in flow communication between said opening and said blower, whereby air from said blower is delivered through and heated by said heating element, impinges upon a receiver member bearing a marking particle image in the opening and is returned to said blower while being substantially prevented from escaping from said chamber.  
     
     
       2. The fusing assembly pre-heater according to  claim 1  wherein said heating element includes at least one resistive heater cell. 
     
     
       3. The fusing assembly pre-heater according to  claim 1  wherein said heating element includes a pair of resistive heater cells respectively including a plurality of conductive fins to provide increased heat transfer properties to said heater cells. 
     
     
       4. The fusing assembly pre-heater according to  claim 1  wherein said impingement member includes a plurality of airflow nozzles. 
     
     
       5. The fusing assembly pre-heater according to  claim 4  wherein said impingement member defines a plurality of airflow return channels located between said airflow nozzles. 
     
     
       6. The fusing assembly pre-heater according to  claim 5  wherein said airflow nozzles respectively define air jet slots oriented transverse to the direction of receiver member travel along said travel path, and said airflow return channels are oriented parallel to said air jet slots. 
     
     
       7. The fusing assembly pre-heater according to  claim 5  wherein said impingement member further includes a low pressure plenum in flow communication with said airflow return channels and said return conduit. 
     
     
       8. The fusing assembly pre-heater according to  claim 1  wherein said impingement member defines a plurality of airflow return channels located between said airflow nozzles, said airflow nozzles respectively defining air jet slots oriented transverse to the direction of receiver member travel along said travel path, and said airflow return channels are oriented parallel to said air jet slots, and said impingement member further including a low pressure plenum in flow communication with said airflow return channels and said return conduit. 
     
     
       9. The fusing assembly pre-heater according to  claim 1  wherein said pre-heater housing includes lead and trail side walls oriented transverse to the direction of travel of a receiver member along said travel path, and outboard side walls opposite outboard marginal edges of said travel path, and wherein said return conduit includes airflow paths respectively defined in said internal chamber adjacent to said lead and trail side walls and said outboard side walls. 
     
     
       10. The fusing assembly pre-heater according to  claim 9  wherein said impingement member further includes a mechanism for forming an airflow vortex respectively adjacent to said lead and trail side walls of said pre-heater housing. 
     
     
       11. The fusing assembly pre-heater according to  claim 10  wherein said vortex-forming mechanism includes respective radius sections located immediately adjacent to, and extending from, said air flow nozzles closest to said lead and trail side walls, the end of each radius section remote from said respective nozzle forming a knife edge. 
     
     
       12. In a fusing assembly for an electrostatographic reproduction apparatus, in which an image-wise pattern of pigmented marking particles is fixed to a receiver member transported along a travel path in operative relation with said fusing assembly, said fusing assembly comprising: 
       a fusing member, located adjacent to said receiver member travel path for heating pigmented marking particles to a degree sufficient to tack such marking particles to a receiver member transported along said travel path;  
       a pre-fusing transport for transporting receiver members to said fusing member; and  
       a pre-heater, for facilitating efficient fusing assembly operation and gloss control, including a housing defining an internal chamber open adjacent to said receiver member travel path opposite said pre-fusing transport, a heating element within said housing internal chamber, an airflow system including a blower, a distribution plenum in flow communication between said blower and said heating element, an impingement member in said chamber opening adjacent to said travel path, an impingement plenum in flow communication between said heating element and said impingement member, and a return conduit in flow communication between said opening and said blower, whereby air from said blower is delivered through and heated by said heating element, impinges upon a receiver member bearing a marking particle image in the opening and is returned to said blower while being substantially prevented from escaping from said chamber.  
     
     
       13. The fusing assembly according to  claim 12  wherein said pre-fusing transport includes a dielectric web, and a charger to apply a charge to said dielectric web sufficient to tack a receiver member thereto for transport therewith. 
     
     
       14. The fusing assembly according to  claim 13  wherein said heating element of said pre-heater includes at least one resistive heater cell, and said at least one resistive heater cell includes a plurality of conductive fins to provide increased heat transfer properties to said heater cell. 
     
     
       15. The fusing assembly according to  claim 13  wherein said impingement member of said pre-heater includes a plurality of airflow nozzles, a plurality of airflow return channels located between said airflow nozzles, and wherein said airflow nozzles respectively define air jet slots oriented transverse to the direction of receiver member travel along said travel path, and said airflow return channels are oriented parallel to said air jet slots. 
     
     
       16. The fusing assembly according to  claim 15  wherein said impingement member further includes a low pressure plenum in flow communication with said airflow return channels and said return conduit. 
     
     
       17. The fusing assembly according to  claim 13  wherein said pre-heater housing includes lead and trail side walls oriented transverse to the direction of travel of a receiver member along said travel path, and outboard side walls opposite outboard marginal edges of said travel path, and said return conduit includes airflow paths respectively defined in said internal chamber adjacent to said lead and trail side walls and said outboard side walls. 
     
     
       18. The fusing assembly according to  claim 17  wherein said impingement member further includes a mechanism for forming an airflow vortex respectively adjacent to said lead and trail side walls of said pre-heater housing. 
     
     
       19. The fusing assembly according to  claim 18  wherein said vortex-forming mechanism includes respective radius sections located immediately adjacent to, and extending from, said air flow nozzles closest to said lead and trail side walls, the end of each radius section remote from said respective nozzle forming a knife edge. 
     
     
       20. The fusing assembly according to  claim 13  wherein said pre-heater housing further includes features to aid in containing the air within said housing, said features including tunnels formed by members extending respectively away from said lead and trail side walls, spaced from and parallel to, said receiver member travel path that serve to increase airflow resistance.